The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Sandwich-type structures, such as honeycomb panels, are used in a variety of applications that require lightweight combined with high strength. Sandwich-type structures generally include a lightweight core with face sheets or skins secured on opposite sides of the core. One such application for sandwich-type structures is in aircraft, and more specifically interior panels of an aircraft such as flooring.
These interior panels are generally secured to the aircraft and/or adjacent components through the use of a specialized fastener generally referred to as an insert. An insert is installed through the core and face sheets in order to provide a location for attaching adjacent components and for transferring associated structural loads. One such example is illustrated in FIG. 1, which shows a mechanical insert 10 installed through a core 12 and face sheets 14 through a thickness “T” of the overall assembly.
Due to inherent manufacturing variation, the overall thickness T of the assembly varies as the core thickness or profile varies, and also as the thickness and profile of each face sheet varies. Additionally, the face sheets are often bonded to the core with an adhesive, and variations in adhesive thickness can also contribute to overall thickness variation of the assembly. When the thickness of the assembly varies, the insert may not be flush with the face sheets on the exterior surfaces of the panel, which can cause stress concentrations and negatively impact the appearance of the panel. If the insert extends above a face sheet, this is known as an “over-flush” condition, which also causes rework because the insert is often subjected to grinding in order to achieve a flush interface between the insert and the face sheet. If the insert is recessed below the face sheet, this is known as an “under-flush” condition, in which the rework often involves drilling out the insert and re-installing an oversize insert. Such rework adds to costs and manufacturing cycle time. Further, when different size inserts are required when the thickness variation is large, such as when an over-flush condition occurs, this adds to inventory and manufacturing assembly time.